The application claims the priority of Japanese Patent Applications No. 2003-44096 filed on Feb. 21, 2003 which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an imaging device assembly for an electronic stereoscopic endoscope system, and, more specifically, to an imaging device assembly comprising a pair of, right and left, solid state image pickup devices that are dispose within a distal end of an insertion section of the endoscope together with a pair of, right and left, objective lens systems.
2. Description of the Related Art
An electronic stereoscopic imaging system for viewing three-dimensional images of an object fundamentally comprises an electronic endoscope for producing two optical images of an object, an electronic processing unit and a viewing system. The electronic endoscope includes a solid state imaging device comprising a pair of, namely right and left, image pick-up modules and right and left objective lens systems housed in a distal end barrel of the electronic endoscope. Each image pick-up module comprises a solid state image sensing element such as a charge coupled device (CCD) for producing a right or a left optical image of an object and converts the optical image into signals. The electronic processing unit processes the signals to generate right and left image signals and alternately provides the right and left image signals to the viewing system which includes a monitor unit and a viewing device such as specially-designed eyeglasses. The monitor unit displays alternating right and left video images corresponding to the alternately-provided right and left image signals on the screen. A properly-equipped viewer of the monitor screen will perceive three-dimensional video images of the object due to the repeatedly alternating left and right video images displayed on the monitor screen.
The solid state imaging device that is installed in the electronic endoscope for use with the electronic stereoscopic endoscope system is known in various forms, and may take any form well known in the art. Such a solid state imaging device disclosed, for example, in Japanese Unexamined Patent Publication No. 2000-199863 includes a circuit board and electronic parts that are disposed behind a solid state image sensing element, more specifically within an open space having the same cross-sectional area as the solid state image sensing element.
Meanwhile, in the recent years, solid state image sensing elements such as a CCD has made remarkable progress and it has turned to reality to provide 1/10 inch microelectronic CCDs for commercial high technology equipments. Such a CCD is about the size of 2×2 mm and is fit to be incorporated as a solid state image sensing element of the image pick-up device in a slenderized electronic endoscope suitable for practical use.
One of the problems that occur in the case where the microelectronic CCDs are used for the imaging pick-up device of the electronic endoscope system is that it is hard to make the electronic endoscope sufficiently small in diameter in relation to sizes of associated electronic parts mounted together with the CCD. That is, in this type of solid state imaging device, it is general to mount resistors, transistors and other electronic parts forming a preamplifier that is connected directly to output terminals of the CCD on a circuit board connected to the CCD. The conventional CCD is large in size over against these resistors, transistors and other electronic parts and, in consequence, has no trouble in arranging these resistors, transistors and other electronic parts within an open space behind the CCD like the solid state imaging device disclosed in the above mentioned publication.
However, in the case where using these electronic parts including resisters and transistors, not custom-made parts but commercially available parts, for a preamplifier, it is hard to arrange these resistors, transistors and other parts orderly within the open space limited behind the 1/10 inch CCD like the solid state imaging device disclosed in the above mentioned publication. This is because, while the 1/10 inch CCD is about 2×2 mm, commercially available transistors measure 1.4×1.2×0.6 mm at the minimum, and commercially available 0.1 W resistors measure 1.6×0.8×0.3 mm at the minimum. Accordingly, as long as using commercially available electronic parts, the dimensional advantage of the microelectronic CCD must be surrendered in light of slenderizing the electronic stereoscopic endoscope.